The present invention is directed to a novel, solid cerium(IV) product and to its utility as an oxidant of aromatic and alkyl substituted aromatic compounds to their corresponding carbonyl group containing compounds. More specifically the solid product described and claimed herein is a cerium methanesulfonate hydroxide hydrate.
Cerium(IV) is a well known oxidant for producing aromatic carbonyl compounds. However, none of the previously known cerium(IV) compounds is ideal for the purpose of achieving fast, selective oxidation of an aromatic compound. For example, anions of certain cerium salts (e.g., chloride, nitrate, perchlorate) are highly reactive with the organic substrate in a manner which cause the formation of large amounts of undesired by-products or exhibit unstable conditions which preclude their use on a commercial scale. Other less reactive anions (e.g., sulfates, acetate, fluoride, boron fluoride, silicon fluoride) generally form salts of low solubility, inhibit the rate of reaction and/or inhibit the ability of the spent oxidant to be readily regenerated. In addition, certain organic acid salts (e.g., benzenesulfonate) are insufficiently stable to be useful in the oxidation of organic compounds.
Although cerous/ceric ions have been known and used in oxidation reactions, there is a need to have a ceric oxidant which can be sufficiently stable under oxidizing conditions to be useful in indirect electrochemical processes, to be capable of undergoing repeated cycling between its cerous and ceric species under a high degree of efficiency, to be a highly selective oxidant in the formation of the desired carbonyl group containing compounds, to be capable of exhibiting high reaction rates to make the process in which they are used commercially attractive, to be a solid stable material capable of being easily transported, stored and metered in necessary quantities and to be capable of readily dissolving in water to provide an aqueous solution.
In a copending application, Ser. No. 859,548 filed May 5, 1986, now U.S. Pat. No. 4,639,298, applicant has described the use of an aqueous solution of cerium methanesulfonate in combination with at least 1.5 molar concentration of free methanesulfonic acid as an oxidation means to achieve high yield and selectivity in the formation of aromatic carbonyl containing compound. The solid ceric material presently described can be used for the same purpose to achieve the same result. It has the advantage of being a solid, easily transportable material which can be stored for extended periods prior to use. When use is desired it readily dissolves to form an oxidant solution.